The California Independent System Operator (CAISO) – the group that manages 80% of the electricity used in California – has begun showing utility-scale batteries charging and discharging into the power grid via their website.

By resolution, due to a natural gas emergency, the State of California requested large-scale battery based energy storage projects be attached to the grid at the end of 2016, early 2017. Now we get to watch the systems – some that we covered – do their job.

On CAISO’s website – find ‘Today’s Outlook’ in the central area of the front page, then click the ‘Click for More’ link. On this page you’ll then click the ‘Supply’ tab in the top center of the page, and scroll down a bit to see the ‘Storage’ section. The graphic shows today’s and yesterday’s data. Energy storage data is also included in the charts above the battery chart as part of overall supply and the renewables volume.

Yesterday, December 26th, the battery storage systems delivered roughly 30MW of power for 45 minutes from 6:15 PM through 7:00 PM. The delivery phase started right around when the duck curve peaked. The hardware continued to mostly deliver small amounts of power through the rest of the evening.

At the peak of demand yesterday, the CAISO monitored grid areas were demanding about 29,000MW. CAISO’s website starts to calculate the ramp period at 3 PM and says the move was 9,596MW. The 30MW peak that the energy storage hardware delivered calculates to just above 0.3% of that 9,596MW difference.

A similar bump occurred in the morning hours yesterday, during the morning time power ramp from the overnight lows. However, the rest of the day saw a lot of up/down charging/discharging.

Thursday, December 21st was a different story though and showed what one might expect from an energy storage system. The tweet below – and my source for this new knowledge – showed the batteries delivering heavy juice in those same morning and evening periods as yesterday, but consistently stayed in the charging window during non-peaks periods.